When talking about comets, we often refer to them as visitors from the outer solar system (or beyond). But not all comets hail from the same place. Some originate from the solar system's most distant region, the spherical cloud of debris loosely bound to the Sun called the Oort Cloud. Such objects include the memorable recent visitor Comet NEOWISE (C/2020 F3; S&T: Nov. 2020, p. 14), which will not return for another 7,000 years. Many other comets, though, originate in the relatively closer Kuiper Belt, a population of small, icy bodies beyond Neptune's orbit. These comets become more frequent repeat visitors to the inner solar system, with orbital periods ranging from a few to about 200 years.
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